1. Field
This application generally relates to signal processing and communication. More specifically, it relates to methods and systems for estimating and/or correcting in-phase (I) and quadrature (Q) communication signal imbalance using signal processing techniques.
2. Background
Wireless communication systems are widely deployed to provide various types of communication content such as voice, data, and so on. These systems may include wireless local area network (WAN) systems exchanging information using various communication techniques. Some of these techniques are focused on methods for transmitting and receiving encoded information. Examples of these techniques include digital modulation techniques such as phase-shift keying (PSK), quadrature amplitude modulation (QAM) and orthogonal frequency division multiplexing (OFDM). Using any of these techniques, a system may encode information into a carrier signal by selectively altering a characteristic of the carrier signal. This information may be decoded by a system receiving the carrier signal with reference to a protocol that defines the meaning ascribed to each carrier signal alteration. Additionally, these modulation techniques may be used in conjunction with various WAN communication standards. For example, OFDM may be used to transmit IEEE 802.11a and IEEE 802.11g packets, as well as in other standards not expressly enumerated herein.
As with any type of communication system, wireless communication systems may suffer from any number of communication inhibitors. More specifically, wireless communications may be inhibited by environmental interference generated by atmospheric conditions and thermal variations. In digital wireless communications, which involve conversion of an analogue signal to a digital signal, quantization error can be a problematic source of interference. OFDM based communications may be further inhibited by phase imbalance between in-phase and quadrature components of the complex baseband signal. These various sources of interference can cause significant signal to noise ratio degradation, resulting in decrease performance and data transfer rates.
There is therefore a need in the art for methods and systems that compensate for the interference caused by these various communication inhibitors.